Some computing applications may store multiple files inside a single file called a file container. For example, software products such as PKZIP® and WinZip® may compress and store multiple files as a single zip file.
Some computer applications may store multiple files in a file container to assist in compartmentalizing information that may have been previously stored in a single file. For example, the Open Packaging Conventions (OPC) is a container-file specification that may be used to store information that in the past may have been stored in a single file. The OPC specification describes how to store Extensible Markup Language (XML) and non-XML files together to form a single file. Microsoft® Word 2007, for example, creates a .docx file that may be a compressed file container that complies with the OPC standard and may contain many files.